There has been an increasing demand for remotely controllable circuit breakers that can reciprocate between an open circuit and a closed circuit in response to a remotely generated command. One advantageous application for such circuit breakers is in the control panel boards that are used for automated control systems such as automated lighting systems. Automated lighting systems have been developed for the control of lighting circuits based upon inputs such as the time-of-day, wall switches, occupancy sensors and/or control from a power distribution system. Lighting control systems offer an opportunity to save energy by automating the process reducing the number of lighting fixtures that are illuminated, or by ceasing artificial lighting altogether when circumstances warrant. For example, ambient light sensors can be used to control lighting circuits in response to ambient light levels. The sensors can serve both switching and automatic dimming functions that can adjust the output of the lighting system continuously in response to the amount of daylight striking the ambient light sensor. Occupancy sensors can be used to activate lighting when someone is in a space and to deactivate the lighting, perhaps after a set time interval, when a person is no longer detected in the space. Using such a system, occupants no longer have to remember to turn the lights off when leaving the space. Automated control systems may require a remotely controllable circuit breaker, or relay. It is desirable that such circuit breakers have a low cost and high reliability.
Standard three-phase electric panel boards are offered in various sizes, the most common of which, but not limited to, are 18 circuits, 30 circuits, and 42 circuits. These standard electric panel boards typically have a phase layout in the order of A-Phase, B-Phase, C-Phase, A-Phase, B-Phase, C-Phase, etc. The order of the phase layout starts from the top continues to the bottom, starting from A-Phase and ending at C-Phase. An example of a normal phase layout for a panel having 18 circuits is: A, B, C, A, B, C, A, B, C.
All electrical lighting must comply with the National Electric Codes (NEC). For example, the provisions of NEC Section 700, apply to electrical safety of the installation, operation and maintenance of emergency systems consisting of circuits and equipment intended to supply, distribute, and control electricity for illumination or power, or both, to required facilities when the normal electrical supply or system is interrupted. NEC code Section 700.12 specifically applies to emergency lighting. NEC code Section 700.12 states that the current supply of electricity shall be such that, in the event of failure of the normal supply of electricity to or within the structure concerned, emergency lighting, emergency power, or both shall be available within the time required for the application but not to exceed a time delay of 10 seconds. NEC code Section 700.12 further states that in a separate and uninterrupted area supplied by a minimum of three normal lighting circuits, a separate branch circuit for unit equipment shall be permitted if it originates from the same panel board as that of the normal lighting circuits and is provided with a lock-on feature.
Circuit breaker panels are also used to protect electrical circuitry from damage due to an over-current condition, such as an overload, a relatively high level short circuit, or a ground fault condition. In order to perform that function, circuit breaker panels include circuit breakers that typically contain a switch unit and a trip unit. The switch unit is coupled to the electrical circuitry (i.e., lines and loads) such that it can open or close the electrical path of the electrical circuitry. The switch unit includes a pair of separable contacts per phase, a pivoting contact arm per phase, an operating mechanism, and an operating handle. In the over-current condition, all the pairs of separable contacts are disengaged or tripped, opening the electrical circuitry. When the over-current condition is no longer present, the circuit breaker can be reset such that all the pairs of separable contacts are engaged, closing the electrical circuitry. In addition to manual over-current protection via the operating handle, automatic over-current protection is also provided via the trip unit. The trip unit, coupled to the switch unit, senses the electrical circuitry for the over-current condition and automatically trips the circuit breaker. When the over-current condition is sensed, a tripping mechanism included in the trip unit actuates the operating mechanism, thereby disengaging the first contact from the second contact for each phase. Typically, the operating handle is coupled to the operating mechanism such that when the tripping mechanism actuates the operating mechanism to separate the contacts, the operating handle also moves to a tripped position.
The general terms “switchgear and switchboard” are used to refer to electrical equipment including metal enclosures that house switching and interrupting or protection devices such as fuses, circuit breakers and relays, along with associated control, instrumentation and metering devices. The enclosures typically include devices such as bus bars, inner connections and supporting structures (generally referred to herein as “panels”) used for the distribution of electrical power. Such electrical equipment can be maintained in a building such as a factory or commercial establishment, or it can be maintained outside of such facilities and exposed to environmental weather conditions. Typically, hinge doors or covers are provided on the front of the switchgear or switchboard sections for access to the devices contained therein. In addition to electrical distribution and the protection of circuitry from over-current conditions, components have been added to panels for the control of electrical power supplied to loads connected to circuit breakers. For example, components have been used to control electrical power for lighting. One system used for controlling electrical power to loads utilizes a remote-operated circuit breaker system. In such a system, the switch unit of the circuit breaker operates not only in response to an over-current condition, but also in response to a signal received from a control unit separate from the circuit breaker. The circuit breaker is specially constructed for use as a remote-operated circuit breaker, and contains a motor for actuating the switch unit.
In an exemplary remote-operated circuit breaker system, a control unit is installed on the panel and is hard-wired to the remote-operated circuit breaker through a control bus. When the switch unit of the circuit breaker is to be closed or opened, an operating current is applied to or removed from the circuit breaker motor directly by the control panel. Additional, separate conductors are provided in the bus for feedback information such as contact confirmation, etc., for each circuit breaker position in the panel. The control unit contains electronics for separately applying and removing the operating current to the circuit breakers installed in particular circuit breaker positions in the panel. The panel control unit also has electronics for checking the state of the circuit breaker, diagnostics, etc. One advantage of that system is that the individual circuit breakers can be addressed according to their positions in the panel. Operation of remote operated circuit breakers requires a means to receive command signals to open or close, report back successful operation or device status, and drive opening and closing of switch mechanism contacts. In order to meet these requirements most efficiently, electronic circuitry is required. Typically, this circuitry is external to the switching device, due to component size and amount of power required. Locating communication and driver circuitry outside the switching device necessitates that the circuitry always be present in the panel board even if the switching device is not.
U.S. Pat. No. 6,034,581 (DiMarco, et al.), the entire disclosure of which is incorporated herein by reference, discloses a contact assembly 22 which is adapted for use with a circuit breaker 12 that is set to open a circuit above a predetermined current load. The contact assembly 22 is adapted to reciprocate between a closed position to permit the flow of current through the circuit and an open position to prevent the flow of current. The contact assembly 22 is further adapted to resist unintended reciprocation from the closed position to the open position at current loads up to or exceeding the predetermined current load. The contact assembly includes a line side conductor 38 and a load side conductor 54. When in the closed position, a surface 42 of the line side conductor 38 extends proximal to a surface 56 of the load side conductor 54 and current flows in substantially the same direction along the line side and load side surfaces 42 and 56 to generate an electromagnetic attraction between the conductors 38 and 54 in order to resist unintended reciprocation of the contact assembly 22 from the closed position to the open position due to inherent repulsion forces present across the contact points (contact constriction forces). U.S. Pat. No. 6,034,581 also describes a circuit breaker assembly 10 and an automated control system 300.
U.S. Patent Publication No. 20080084644 (William A. King), the entire disclosure of which is incorporated herein by reference, discloses an electrical distribution system for selectively connecting an electrical power source to load devices comprising a panel board having a plurality of load circuit positions. A remote operated device is mountable in the panel board comprising a load control device, and a device control for controlling the load control device. The device control comprises a programmed controller for operating the load control device responsive to control commands and a communication circuit for receiving control commands. An input/output (I/O) controller is mounted in the panel board for controlling operation of the remote operated device. The I/O controller comprises a programmed controller for generating the control commands for commanding operation of the remote operated device. The control system includes a communication circuit for communication with the remote operated device communication circuit.
There are commercially available emergency light fixtures that combine normal lighting and emergency lighting in one fixture. These light fixtures require two separate AC power inputs from the electrical panel board. A first AC input is for the normal lighting, which may require a remotely controlled circuit breaker or relay. A second AC input is for the emergency lighting. This second AC input provides power for charging the internal battery located in the fixture, and for powering the fixture's internal control circuits that sense loss of power from the electrical panel board and activate the emergency lighting circuits powered by the internal battery.
What is needed is an emergency lighting system that overcomes the aforesaid problems of the prior art.